The present invention relates to a pressure valve for fuel injection pumps.
Pressure valves of the type under discussion are normally positioned in a fuel delivery or fuel supply conduit between a pump working chamber of the fuel injection pump and an injection valve of the internal combustion engine.
The pressure valve of the foregoing type has been disclosed for example in U.K. Pat. No. 1,445,750. The known pressure valve includes a cup-shaped valve locking element, the end face of which at the open end of the cup-shaped locking element is formed as a sealing surface, and the valve locking element is guided in a tubular valve member and has a valve seat at the injection pump-side end at the inner bore of reduced diameter of the tubular valve member. The cup-shaped locking element further includes in its bottom an axial bore which is controlled by the closing member of the pressure relief or check valve. This axial bore is not formed as a throttle. The object of such conventional construction has been to provide a damage-resistant valve with a non-detachable support for the storing spring of the pressure relief valve and to prevent the penetration of great particles into the pump working chamber in the case of failure of the structural components of the pressure valve. For this purpose the valve member of the known valve has a base which is formed with a through bore to enable the fuel passage to be formed around the support of the compression spring of the check valve. With this known construction specifically the support of the compression spring of the relief valve is arranged at the level of the seat surface in the valve member. The known pressure valve assembly, however, makes it difficult to adjust a prestressing of the compression spring of the relief valve. Supporting discs or washers have been employed for this purpose, which, on the one hand, have reduced the cross-section of the through passage at the base of the valve member, and, on the other hand, have hindered the movement of the valve locking element of the pressure valve.